#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:fenc=utf-8
#
# Copyright © 2019 crane <crane@gosun>
#
# Distributed under terms of the MIT license.

"""
https://www.luogu.org/problem/P3629
https://blog.csdn.net/SSL_ZYC/article/details/84670545
"""


def main():
    print("start main")

if __name__ == "__main__":
    main()
